Urinary incontinence or the loss of bladder control is a common and often embarrassing problem. The severity of urinary incontinence ranges from occasionally leaking urine when one coughs or sneezes to having an urge to urinate that is so sudden and strong one does not get to a toilet in time.
The three main types of urinary incontinence are: stress incontinence: occurs during certain activities like coughing, sneezing, laughing, or exercise; urge incontinence: involves a strong, sudden need to urinate followed by instant bladder contraction and involuntary loss of urine; and overflow incontinence: occurs when the bladder cannot empty completely, which leads to dribbling.
Incontinence is most common among the elderly. Women are more likely than men to have urinary incontinence. Infants and children are not considered incontinent, but merely untrained, up to the time of toilet training. Occasional accidents are not unusual in children up to age 6 years. Young (and sometimes teenage) girls may have slight leakage of urine when laughing. Nighttime urination in children is normal until the age of 5 or 6.
Normally, the bladder begins to fill with urine from the kidneys. The bladder stretches to allow increasing amounts of urine. The first urge to urinate occurs when around 200 mL of urine is stored in the bladder. A healthy nervous system will respond to this stretching sensation by alerting the urge to urinate, while also allowing the bladder to continue to fill. The average person can hold around 350 to 550 mL of urine. Two muscles help control the flow of urine: the sphincter must be able to squeeze to prevent urine from leaking. The bladder wall muscle (detrusor) must stay relaxed so the bladder can expand. When it is time to empty the bladder, the bladder wall (detrusor) muscle contracts or squeezes to force urine out of the bladder. Before this muscle squeezes, the body must be able to relax the sphincter to allow the urine to pass out of the body.
The ability to control urination depends on having normal anatomy, a normally functioning nervous system, and the ability to recognize and respond to the urge to urinate.